Alkali metal tripolyphosphate products



United States Patent 3,337,468 ALKALI METAL TRIPOLYPHOSPHATE PRODUCTS Joe S. Metcalf, Chesterfield, and Kenneth J. Shaver and Chung Yu Shen, St. Louis, Mo., assignors to Monsanto Company, St. Louis, Mo., a corporation of Delaware No Drawing. Filed Feb. 17, 1966, Ser. No. 528,051

11 Claims. (Cl. 252139) This invention relates to processes for producing detergent compositions. More particularly, it relates to processes for producing detergent compositions containing alkali metal tripolyphosphates which are produced from alkali metal trimetaphosphates.

This application is a continuation-in-part of our copending application Ser. No. 200,658, filed June 7, 1962, now abandoned.

Belgian Patent No. 633,146, issued Dec. 2, 1963, discloses processes for producing detergents containing alkali metal tripolyphosphates and for producing products which are essentially alkali metal tripolyphosphate but contain a small amount of a foaming agent. These processes involve reacting an alkali metal trimetaphosphate with a strong base in the presence of a foaming agent in an aquetous medium and thereafter removing the water to form a solid material. By conducting the reaction in the presence of proper amounts and kinds of surface active agents, a built detergent composition is produced. However, if it is desired to produce a product which is essentially alkali metal tripolyphosphate for subsequent use in a detergent formulation only a small amount of a foaming agent is added.

As is disclosed in Belgian Patent No. 633,146, these processes and products have several advantages over the prior processes, however, the products produced generally tend to be somewhat fragile and therefore tend to physically degrade upon repeated handling particularly when the products contain more than 50% by Weight of alkali metal tripolyphosphate. An improvement to the processes that are disclosed in the foregoing Belgian patent that would enable products to be produced which have an improved resistance to physical degradation would be a significant advance in the art.

It is, therefore, an object of this invention to provide an improved process for producing detergents containing alkali metal tripolyphosphates.

It is an additional object of this invention to provide an improved detergent product containing alkali metal tripolyphosphates.

Other objects of this invention will become readily apparent to one skilled in the art from the following detailed description.

In accordance with this invention an alkali metal trimetaphosphate is reacted with a strong base in the presence of a foaming agent to produce a particulate product containing alkali metal tripolyphosphate and at least a portion of the reaction is conducted in the presence of a relatively minor amount of one or more nonvolatile organic compounds of a class to be hereinafter defined. The resulting product has a significantly improved resistance towards physical degradation as compared to products produced without the addition of such nonvolatile organic compounds.

The organic compounds which have been found to be useful in the practice of this invention are the monohydric and polyhydric alcohols which have a boiling point above about 150 C. It is generally preferred to employ those foregoing compounds which have a melting point below about 100 C.

The monohydric alcohols which are nonvolatile and useful in this invention are those saturated aliphatic alcohols which generally contain from about 6 to about 18 carbon atoms, that is, the higher alkyl alcohols. Also included as higher alkyl monohydric alcohols are the relatively pure higher alcohols such as n-octyl alcohol, n-decyl alcohol, dodecyl alcohol, hexadecyl alcohol and the mixed alcohols which are derived from fatty oils and are actually a mixture of various alcohols having varying chain lengths but average a given length such as lauryl alcohol (C myristyl alcohol (C cetyl alcohol (C and the like.

Nonlimiting examples of the foregoing useful monohydric alcohols include n-hexyl, n-heptyl, n-octyl, nnonyl, n-decyl, dodecyl, tetradecyl, octadecyl, and the like, and the mixed alcohols, such as lauryl, myristyl, cetyl, palmityl, stearyl, oleyl, caprylyl, capryl, and the like.

Although any of the higher alkyl monohydric alcohols can be used, it is preferred to use those monohydric alcohols containing from about 10 to about 16 carbon atoms and especially prefered to use the C to C mixed monohydric alcohols such as those derived from fatty oils.

The polyhydric alcohols which have boiling points and melting points such that they are nonvolatile and therefore useful in the practice of this invention generally contain from about 2 to about 8 carbon atoms.

Nonlimiting examples of the foregoing useful polyhydric alcohols containing from 2 to 8 carbon atoms include ethylene glycol; propylene glycol; glycerol; l,2propanediol; 1,3-propanediol; l,2-butanediol; l,3-butanediol; 1,4-but-anediol; pentamethylene glycol, hexarnethylene glycol and the like.

It is preferred, however, to use polyhydric alcohols containing from 2 to about 6 carbon atoms with ethylene glycol, propylene glycol and glycerol being especially preferred because of their relatively inexpensiveness and availability.

Although the advantages of this invention can be achieved with as little as .025% by weight based upon the product produced of the nonvolatile compounds, it is generally preferred to incorporate at least about 0.5% by weight to obtain significant improved resistance towards physical degradation; and it is further preferred to incorporate amounts from about 1 to about 8% by weight. However amounts greater than 8% by weight, such as 10% or even 20%, can be used. Amounts greater than about 8 weight percent do not produce any additional beneficial results and needlessly add to the cost of the product, therefore are not recommended.

There can be employed in accordance with this invention any of the foaming agents, alkali metal trimetaphosphate, and additives disclosed as being suitable in the above mentioned Belgian patent application 633,146. The process conditions employed in the practice of this invention are generally the same as disclosed in Belgian Patent 633,146. However in some instances, it may be advantageous to employ as little as about 0.01% by weight of the foaming agent.

Thepreferred foaming agents in the practice of this invention are the water soluble soaps, water soluble alkyl aryl sulfonates, water soluble alkyl sulfates, which are well known anionic detergent actives. Examples of nonionic active foaming agents which are preferred are the alkali metal salts of sulfated ethylene oxide or propylene oxide condensation products manufactured by ethoxylating propylene and subsequently sulfating various organic hydrophobic compounds containing active hydrogen such as alcohols, mer-captans, phenols, and amines; sodium and potassium alkyl glyceryl ethers; alcohol-alkylene oxide condensates; and alkylphenol-alkylene oxide condensates. Of these, those in the anionic class are preferred, while the fatty alkylol sulfates alkyl aryl sulfonates and fatty acid soaps having from 8 to 20 carbon atoms in their carbon chains are further preferred in the process of this invention.

Any suitable manipulative procedure resulting in the portion of the reaction of the alkali metal trimetaphosphate with a strong base being conducted in the presence of a foaming agent and a. nonvolatile organic compound of the class herein described can be employed in accordance with this invention. One relatively easy method of practicing this invention is to add the nonvolatile material to an aqueous slurry of the alkali metal trimetaphosphate prior to the addition of strong base and foaming agent. However, since the reaction rate of trimetaphosphate with a strong base is relatively slow at room temperature, it is possible to form an aqueous slurry of the alkali metal trimetaphosphate, foaming agent, strong base, and the nonvolatile material in water at relatively low temperature, that is, below 30 C., and heat the slurry to complete the conversion of alkali metal trimetaphosphate to alkali metal tripolyphosphate. Also, if it is desired, the material other than the alkali metal trimetaphosphate slurry can be slurried together, heated to about 40 C. and alkali metal trimetaphosphate added thereto.

In general, the products which tend to be fragile and physically degrade without the benefits of this invention are those which contain at least 50% by weight of the alkali metal tripolyphosphate, therefore, this invention will normally be used on such processes. However in certain instances, some benefits can be derived when the product contains less than 50% by weight of the alkali metal tripolyphosphates. Additionally sodium tripolyphosphate is the most commonly used of the alkali metal tripolyphosphates, the process improvement of this subject invention will generally be employed in the production of products containing sodium tripolyphosphate, however this improvement applies equally well to all processes for producing other alkali metal tripolyphosphates such as potassium and lithium wherein an alkali metal trimetaphosphate is reacted with a strong base in the presence of a foaming agent to thereby form a product containing alkali metal tripolyphosphate.

To more fully illustrate the subject invention, the following nonlimiting examples are presented. Unless otherwise specified, all parts, proportions, and percentages are by weight.

Example I About 1,000 parts of sodium trimetaphosphate are slurried in about 860 parts of water in an agitated vessel to form a slurry containing about 55% solids and containing about 2% by weight of sodium lauryl sulfate. The foregoing slurry is preheated to about 60 C. and then about 50 parts of glycerol and about 525 parts of 50% sodium hydroxide are added. Within about 30-60 seconds the temperature increases to about 100 C. at which time agitation is shut off. The release of steam from the reacting slurry causes the volume of the reaction mass to increase several fold. In about 4 to 10 minutes, the reaction is completed and the mass begins to cool and the evolution of steam stops. The material is then air dried.

The sodium tripolyphosphate material containing the glycerol when subjected to a frangibility test as described below produced only about 40% of the amount of fines (particles which will pass through a US. Standard 100 mesh screen) that was produced with similar material produced in a similar manner but without the glycerol which was subjected to a similar test.

A sample frangibility test has been developed to measure the tendency of the product to break into smaller fractions during handling. The test consists of placing about 100 grams of material having a particle size larger than a US. Standard 100 mesh screen on a 100 mesh screen, adding three rubber balls and shaking for a definite time interval and after the shaking period measuring the amount of material that passes through the mesh screen. Standard laboratory screens and pure gum rubber balls 1%" in diameter are used in the before-mentioned test. By strict adherence to the weight of material tested and the time intervals for shaking the accuracy of the above test is about plus or minus 0.3 to 0.5%; that is, the amount of material that degrades to smaller than 100 mesh in two samples of the same material when each are subjected to the before-mentioned test will measure within 0.3% to 0.5% of each other.

Other comparable compositions can be prepared in the same manner as described above by replacing glycerol with similar amounts of other oxygen containing organic compounds useful in practicing this invention. For example, similar amounts of ethylene glycol, propylene glycol, 1,2-propanediol, 1,2-butanediol, pentamethylene glycol and hexamethylene glycol can be substituted for glycerol in the foregoing process and the product produced has substantially improved frangibility properties over that produced without the addition of a polyhydric alcohol.

Example 11 An improved sodium tripolyphosphate product is produced in the following manner. About 368 parts of sodium trimetaphosphate are slurried in about 224 parts of water in an agitated vessel to form a slurry containing about 62% solids. About 4 parts of soap flakes from a tallow base amounting to about 0.7% of the finished product are added and the mixture is heated to about 40 C. and about 6 parts of ethylene glycol are added. Following the addition of the ethylene glycol, about 192 parts of 50% sodium hydroxide are added. The temperature of the reaction mixture increases to above about 100 C. and the agitation is shut off at the time of the first evolution of steam The reaction is completed within about 10 minutes and the porous mass formed by the evolution of steam begins to cool. After the material is cooled to room temperature, it is removed from the vessel and air dried.

Using the frangibility test as described in Example I, the material of this example produces about 40% of the amount of fines produced by similar material without ethylene glycol.

Substantially similar results are achieved by using the same procedure when other polyols, such as 1,2-propanediol, 1,3-propanediol, hexamethylene glycol and 1,4-butanediol are substituted for the ethylene glycol of the above example.

Example 111 Into a mixing vessel which is fitted with a conventional paddle type stirrer and jacketed so that either hot or cold water or steam can be used in the jacket are charged 400 parts of water, 120 parts of sodium dodecylbenzene sulfonate, 50 parts of sodium lauryl sulfate, 300 parts of sodium sulfate, 420 parts of sodium trimetaphosphate, and 15 parts of lauryl alcohol. The resulting slurry is stirred for about 20 minutes to insure thorough mixing and the temperature is raised to about 70 C. by circulating the steam through the jacket.

After the temperature reaches about 70 C. about 220 parts of sodium hydroxide are added to the slurry. After about 30 seconds, the temperature of the slurry begins to rise. The agitation is discontinued when the temperature reaches about 90 C. When the temperature reaches about C., the slurry begins to expand and steam is evolved from the mass. Within about 10 minutes, the reaction mass begins to solidify. After being air dried overnight to remove most of the excess free water, the detergent product is a free-flowing, noncaking material and has a bulk density of about 0.6 gram per cc.

Using essentially the same process as described above, a detergent mixture is prepared without the lauryl alcohol. The bulk density of the material is about 0.35 gram per cc. and when subjected to a frangibility test similar to that described in Example I produces about 30% more fines than the material with the lauryl alcohol.

Substantially similar results are obtained by substituting about 1% by weight based upon the final roduct of either a C -C mixed" alcohol or a C14-C18 mixed alcohol for the lauryl alcohol.

What is claimed is:

1. In a process wherein an alkali metal trimetaphosphate is reacted with a strong alkali metal base in an aqueous reaction medium and in the presence of a foaming agent to thereby produce a particulate product containing an alkali metal tripolyphosphate, the improvement which comprises incorporating into said reaction medium a nonvolatile alcohol having a boiling point above about 150 C. said alcohol being selected from the group consisting of monohydric alcohols containing from 6 to 18 carbon atoms and polyhydric alcohols, containing from 2 to 8 carbon atoms, said alcohol being present in amounts suitable to prevent physical degradation of the final product.

2. An improved process according to claim 1 wherein said nonvolatile alcohol is higher ialkyl alcohol containing from about 10 to about 16 carbon atoms and is present in amounts of at least about 0.5% by weight based on the weight of the product produced by said process.

3. An improved process according to claim 2 wherein said nonvolatile alcohol is lauryl alcohol.

4. An improved process according to claim 1 wherein said nonvolatile alcohol is a polyhydric alcohol containing from 2 to about 6 carbon atoms and is present in amounts of at least about 0.5% by weight based on the weight of the product produced by said process.

5. An improved process according to claim 4 wherein said nonvolatile alcohol is glycerol.

6. An improved process according to claim 4 wherein said nonvolatile alcohol is ethylene glycol.

7. In a process wherein sodium trimetaphosphate is reacted with sodium hydroxide in an aqueous reaction medium and in the presence of at least about 0.01% by weight of a foaming agent based upon the weight of the reaction medium and wherein a product containing at least about by weight of sodium tripolyphosphate is produced, the improvement comprising incorporating into said recation medium a nonvolatile alcohol selected from the group consisting of monohydric alcohols having from about 6 to about 18 carbon atoms and polyhydric alcohols having from 2 to about 8 carbon atoms, said nonvolatile alcohols having a boiling point above about 150 C. and being present in amounts of from about 1% to about 8% by weight based upon the weight of the product produced by said process.

8. An improved process according to claim 7 wherein said nonvolatile alcohol is a polyhydritc alcohol having a melting point below about C. and containing from 2 to about 6 carbon atoms.

9. A process according to claim 7 wherein said nonvolatile alcohol is a higher alkyl alcohol having a melting point below about 100 C. and containing from about 10 to about 16 carbon atoms.

10. A process according to claim 9 wherein said nonvolatile alcohol is added to an aqueous slurry containing sodium trimetaphosphate prior to the addition of the sodium hydroxide.

11. A composition produced aocording to the process of claim 7.

References Cited UNITED STATES PATENTS 2,365,190 12/1944 Hatch 252 2,874,123 2/1959 Schaafsma et al. 25299 2,878,190 3/1959 Dvorkovitz et a1. 252137 X 2,941,948 6/1960 Blinka et a1. 252135 X LEON D. ROSDOL, Primary Exdminer.

J. T. FEDIGAN, Examiner. 

1. IN A PROCESS WHEREIN AN ALKALI METAL TRIMETAPHOSPHATE IS REACTED WITH A STRONG ALKALI METAL BASE IN AN AQUEOUS REACTION MEDIUM AND IN THE PRESENCE OF A FOMING AGENT TO THEREBY PRODUCE A PARTICULATE PRODUCT CONTAINING AN ALKALI METAL TRIPOLYPHOSPHATE, THE IMPROVEMENT WHICH COMPRISES INCORPORATING INTO SAID RECTION MEDIUM A NONVOLATILE ALCOHOL HAVING A BOILING POINT ABOVE ABOUT 150* C. SAID ALCOHOL BEING SELECTED FROM THE GROUP CONSISTING OF MONOHYDRIC ALCOHOLS CONTAINING FROM 6 TO 18 CARBON ATOMS AND POLYHYDRIC ALCOHOLS, CONTAINING FROM 2 TO 8 CARBON ATOMS, SAID ALCOHOL BEING PRESENT IN AMOUNTS SUITABLE TO PREVENT PHYSICAL DEGRADATION OF THE FINAL PRODUCT. 